The New Science of Hair Growth

Brandishing a syringe the size of a caulking gun, hair-transplant surgeon James Harris, M.D., injects local anesthetic into the scalp of a male patient, a married financial analyst in his early forties who has asked not to be identified. We'll call him Scott. For 5 hours, I've been watching Dr. Harris perform a hair transplant called surgically advanced follicular extraction, or SAFE. A follicular unit is a miniature, self-contained hair factory embedded in the skin. Each square centimeter of human scalp contains 80 to 120 follicular units, and each of those has one to four hairs.

Though Scott is sitting upright, his scalp is a gruesome battlefield. Rivulets of blood seep from thousands of BB-size puncture wounds. A trash can is brimming with blood-soaked gauze. But Scott feels nothing. He's watching CNBC's financial roundup on a wall-mounted TV while thumbing through e-mails on his BlackBerry, oblivious to the mayhem topside.

Dr. Harris is using a motorized tool he designed himself, in a procedure that, for all its bloodshed, represents the current state-of-the-art in baldness treatment. The instrument has a blunt hollow tube that lets Dr. Harris make incisions less than a millimeter wide, in rapid-fire succession, around clusters of hairs without damaging the underlying follicles. It's painstaking work. I watched earlier as Dr. Harris donned mantislike headgear (dual loupes with six-fold magnification) and extracted follicular units from a band of hair between Scott's ears, a region of scalp hair docs call the "horseshoe fringe." In virtually all men, this fringe is impervious to balding, a vestigial result of genes that dictate how skin forms during fetal development.

By the time he's through, Dr. Harris will have made 1,045 incisions along the front and top of Scott's head, enough to accommodate the same number of follicular units removed from his fringe. An assistant counts the extracted follicular units under a microscope, tabulating the number of individual units and the number of hairs protruding from each one. Single-hair units are reserved for the front to create a feathered widow's peak. "I want to avoid a wall of hair jutting from the forehead," Dr. Harris explains, citing a common blunder of botched transplants. "SAFE is a lot less traumatic than other transplant procedures, such as a surgery in which a strip of scalp is extracted, because it's minimally invasive." Even so, the procedure looks medieval, and it's hard to believe this gory mélange will have a happy ending.

Hair transplants have improved dramatically in the past 10 years, although in the hands of unskilled surgeons, mishaps can occur that leave patients with gruesome doll heads. But transplants remain hamstrung for a more fundamental reason: You can shuffle only so many hairs from fringe to forelock. This is Scott's fourth surgery, and at this point he's simply running out of hair. It's a dwindling game of musical chairs that confounds surgeons and frustrates patients. The average age for undergoing a hair transplant is 40, but hair is doomed long before that. To be precise, its fate is decided in utero, during the tenth week of pregnancy, when the human fetus is the size of a peanut shell. That's when the fingers and toes take shape and the brain starts to evolve. It's also when the hair follicles form—roughly 5 million over the entire body. This number is fixed: After exiting the womb, the human body can't produce a single additional follicle.

That's why a revolutionary technique known as hair cloning, or hair multiplication, holds so much promise. It changes the game because it gives transplant surgeons an endless supply of follicular units to restore the vanishing manes of their patients. Researchers in a handful of labs around the world have been testing the technique on mice with impressive results. Several start-ups have formed, and these companies are racing to complete successful human clinical trials.

It could have a profound effect on the landscape: Male-pattern baldness, or androgenetic alopecia, affects 40 million men in America. Although it doesn't have any known physical downsides, the specter of premature aging and the perception of waning virility and diminished sexual attractiveness can be mentally debilitating, and lead to personal, social, and work-related problems, according to Nigel Hunt, Ph.D., an associate professor of applied psychology at the University of Nottingham, in England.

In 66 percent of men, hair follicles start to shrink around age 35 (in some men, it starts at age 21), causing hair to thin. By age 50, hair follicles are dying and 85 percent of men have significantly thinning hair. For these men, the cure for balding can't come soon enough.